A Syrian-Kurdish militia and a group monitoring the Syrian war have said Islamic State used poison gas in attacks against Kurdish-controlled areas of north-east Syria in late June. The Kurdish YPG militia said ISIS had fired “makeshift chemical projectiles” on 28 June at a YPG-controlled area of the city of Hasakah, and at YPG positions south of the town of Tel Brak to the north-east of Hasakah. In January, Kurdish sources in Iraq said that ISIS used chlorine gas as a chemical weapon against Kurdish peshmerga fighters on 23 January. In the previous Islamist insurgency in Iraq – in Anbar province, in 2006-2007 – there was evidence of chemical use by the insurgents. The insurgents in 2006-2007 were members of al-Qaeda in Iraq, which later transformed itself into ISIS.

A Syrian-Kurdish militia and a group monitoring the Syrian war have said Islamic State used poison gas in attacks against Kurdish-controlled areas of north-east Syria in late June.

The Kurdish YPG militia said ISIS had fired “makeshift chemical projectiles” on 28 June at a YPG-controlled area of the city of Hasakah, and at YPG positions south of the town of Tel Brak to the north-east of Hasakah.

Redur Xelil, the YPG spokesman, told the Guardian on Saturday that the type of chemical used had not yet been definitively identified. No YPG fighter exposed to the gas had died because they were quickly taken to hospital and treated, he added.

He noted that this was the first time ISIS had used poison gas against the YPG.

The Syrian Observatory for Human Rights, a U.K.-based group which relies on activists on the ground in Syria to issue what analysts regard as reliable reports on the war, said it had also documented the use of poison gas by ISIS in an attack on a village near Tel Brak on 28 June.

The human rights group said twelve YPG fighters had been exposed to the gas. The group also said it had received information about the gas attack on Hasakah, but gave no further details.

The YPG statement could not be verified by other sources, but the YPG said it was asking for the help of an international team of experts to investigate ISIS’s use of chemical weapons.

Back in January, Kurdish sources in Iraq said they had evidence that (ISIS) used chlorine gas as a chemical weapon against Kurdish peshmerga fighters. The Kurdistan Region Security Council said the chlorine gas was spread by a suicide truck bomb attack on 23 January in northern Iraq. Iraqi officials and Kurds fighting in Syria have made several similar allegations since last fall about ISIS using chlorine chemical weapons against them. In the previous Islamist insurgency in Iraq – in Anbar province, in 2006-2007 – there was evidence of chemical use by the insurgents. The insurgents in 2006-2007 were members of al-Qaeda in Iraq, which later transformed itself into ISIS (see “ISIS employed crude chemical weapons against Kurdish Peshmerga,” HSNW, 16 March 2015).

The YPG is the armed wing of the Syrian branch of the PKK, the pro-independence Turkish Kurdish faction. The YPG has been receiving military aid and training from the United States, but neighboring Turkey regards it as a terrorist organization because of its ties to the PKK.

YPG fighters have pushed ISIS back from a large swath of territory in north-eastern Syria with the help of U.S. air strikes. Areas captured from Isis include the town of Tel Abyad at the border with Turkey.

The YPG said in a statement that its forces had captured industrial-grade gas masks in the last four weeks from Isis fighters, “confirming that they are prepared and equipped for chemical warfare along this sector of the front.”

The group’s statement also said that its fighters who were exposed to the gas “experienced burning of the throat, eyes and nose, combined with severe headaches, muscle pain and impaired concentration and mobility.”

“Prolonged exposure to the chemicals also caused vomiting,” the statement added.